We propose to study the absorption spectra of metalloporphyrins and of other iron series transition metal complexes in the region of the metal M11,111 edge by yield spectroscopy. This region often displays discrete features below the edge which are related to the various states of the complex of the next element in the periodic table (core analogy). Thus we can obtain an overview of the states of the core analogue complex which contain substantial metal d or s amplitude. The distributions and compositions of these states are important in determining the chemistry about the metal center, and thus in determining the function of the porphyrin.